engleski

GEOPOLYMERIC MATERIALS PREPARED USING CLASS F FLY ASH

The utilisation of coal-fly ash, as a basic ingredient of a new geopolymeric material, has been receiving an increasing attention of researchers. The present work reports the results of the study of the influence of different curing conditions on the strength development and phases formed in geopolymeric materials prepared using the Croatian coal-fly ash (ASTM Class F) and sodium silicate solution (water glass, technical grade). The reaction products formed during alkaline activation of fly ash have been characterized by X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). The results of the investigation show that the aluminosilicate active component of fly ash used reacted with water glass and that the main products in the geopolymeric materials was amorphous alkali aluminosilicate gel. The optimum condition was found to be after 24 h of heat curing at 85 oC. Mortar compressive strength measurements show a maximum strength of almost 8 MPa after 7 days. In addition, the evolution of mechanical properties of prepared geopolymers has also been discussed in terms of products formed at different times of reaction.

Fly ash; alkali activation; geopolymers; mechanical strengths; mortar; XRD; FTIR.

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